Boxing for cementitious molds



Dec. 23, 1941. H. FOWLER ETAL 2,267,329

BOXING FOR CEMENTITIOUS MOLDS INVENTOR.

HAROLD L. F WLER Aueusr L. WEYH/NG M4. 012,

A-n-nRNEY Patented Dec. 23, 1941 UNITED STATES PAT ENT. OFFICE BOXINGFOR CEMENTITIOUS MOLDS Harold L. Fowler, Oak Park; Ill., and August L.Weyhing, Louisville, K'y., assignors to Edmund A. Steinbeck, Louisville,Ky. f a v Application August 1, 1940, :Serial No. 349.196

(Clea-9'7) -10 Claims.

This invention relates to means for holding a cementitious mass ofinvestment materialwhile the same issetting and hardening around a waxpattern or model which wax pattern or model is subsequently evaporatedand a metallic cast thereof made and which means or mechanism may betermed a boxing for cementitious molds. The boxing for cementitiousmolds herein described will probably find its primary use in the makingof molds for dental castings and its use will be described inthis.eonnection. In the past it has been customary to make the boxing ofsheet wax which required considerable amount of patient work andresulted .in the destruction of the wax and thereby increased the costof the mold. Frequently the castings to be made have undercut sectionsor portions and other extremely thin sections and with the boxing aspreviously used no assurance was had that the investing mold materialwas properly surrounding and contacting these parts.

By the present invention there is provided a boxing which can berepeatedly employed for forming the mold and readily adapts itself tothe use of flexible transparent material whereby the operator canreadily see where his investing a mold material is going and has theassurance that his resulting casting will have all of the properundercuts and this section portions thereon.

It is therefore one of the chief objects of this invention to provide aboxing for forming cementitious molds thatmay be readily set uppreparatory to use.

Another object of this invention is the provision of a boxing forcementitious molds that can be used over and. over again and reducing toa minimum the time involved in making a cementitious mold.

' Another objectof thisinvention is the provision of a mechanism foraccomplishing the objects above and in which use may be readily made oftransparent material for forming' the walls of the boxing so that theoperator can readily see the fiow of the cementitious mass that anymodificationmay be made in the exact structuralfdetails there shownv anddescribed, within the scope of the appended claims, without departingfrom or exceeding the spirit of the invention.

" In the drawing:

Fig. 1 is an elevational view of one form of the boxing forming thesubject matter of this invention. 1

Fig. 2 is a top plan view of the boxing of Fig. 1. v Fig. 3 is asubstantially central horizontal sectional view taken on line 3-3 onFig- 1.

Fig. 4 a viewpartly' in section andpartly in elevation, asseefisubstantially from line 4-4 onFig.3. I 9

Fig, 5 is a'prospective view of the key for tightening the curtain whichforms the wall ofthelbox.

Fig. 6 is a View, similar to Fig. 1, of a second form ofboxing formingthe subject matter of this invention.

Figs. '7 and 8 are horizontal sectional views through the modifiedboxing of Fig. 6 and as seen respectively on line 1-"! and 8-8 on saidFig 6. 1

Fig.9 for a vertical sectional view through the modified'boxing as seenon line 9-9 on Fig. 8.

. Fig. 10 is an elevational view of the opposite ends of the curtainforming the sides of the modified boxing of Fig. 6.

Throughout the several views of the drawing similar reference charactersare employed to denote the same or similar parts.

As was noted above the mechanism of this in- Vention may be termed aboxing for cementitious molds that is a structure which holds theocmentitious material while setting or hardening around the pattern ormold during and while it is being invested. 0

It is also-an object of this invention to provide, such a boxing whichcomprises a minimum number of parts and all of which have relativeconjunction with the accompanying drawing forming a part-thereof and itis to be understood from its initial semi-fluid-state to its set formand'at the same timesupports the pattern or model around which thecementitious material is poured. As will later be made clear this boxingis supported on a vibrator so that the mold material which is pouredinto the boxing flows into all of the crevices and undercuts on thepatternfl Specifically, and referring to the drawing, the boxing of thisinvention comprises a base member l5 conveniently formed of a metalcasting and hollowed for lightness. The upper end of the base is flat asat l6 and the lower end has a projecting rib I! to form a shoulder l8and upstanding from said base is a post [9. The post [9 may beintegralwith the base IE but for convenience in manufacture is formedseparately from the base and let into a socket 20 in the base and heldtherein by suitable screws 2|.

As seen in Figs. 1 to 4 inclusive, the post H! has outwardly projectingfrom its upper and lower ends, respectively, an ear 22 and 23 eachprovided with an aperture 24 inalignment with one another. The ear 22 isprovided at right angles to its aperture 24 with a tapped aperture 25receiving the threaded end of a thumb screw 26. In order to finish offthe base I5 its lower open end is closed by a base plate 21 pinned orotherwise secured to the flange of the said base l5.

Passing through the aligned apertures 24 in the cars 22 and 23 is a keyindicated in general by the reference character 28 and illustrated mostclearly in Fig. 5. The key 28 comprises a relatively long circular bodyportion 29 having substantially throughout its length a slit or slot 30thereby providing arms 3| and 32. At the upper end of the body portion29 is a collar 33 having a shoulder 34 at its lower end which rests onthe upper surface of theear 22 and thereby limits the movement of thekey 28 through the cars 22 and 23. Beyond the collar portion 33 is aknob 35 serrated for the operator's convenience in readily turning thekey 28 in its apertures Secured to the back surface of the post 19 as byscrews 36, is one end 3'! of, what may be termed for want of a bettername, a curtain 3B, which forms the Walls of the boxing. The curtain 38is formed of sheet material which can be readily bent around the base I5and drawn tightly thereagainst and has its lower edgeresting on theshoulder or. ledge I8 formed by the annular rib I1. It is preferablethat this ourtain be transparent and non-porous with its inner and outersurfaces smooth. In practice it has been found that sheet Celluloidmakes an ideal material for this purpose since it embodies all of theabove characteristics. It is, of course, understood that other types ofmaterial having these same characteristics may be employed such as thenewer thermo-plastic materials as used in a wide variety of instances..The other end 39 of the curtain 38 isnot fastened except by the key 28as will be later made clear.

The operation of the mechanism is as follows:

Reference is had to Fig. 9 which shows in broken lines the operation 'ofthis mechanism which is identical whether the boxing illustrated inFigs. 1 to 5 inclusive is employed or the boxing later to be describedin detail and illustratedin Figs. 6 to inclusive is employed.

Mounted on the. surface l6 of the base J5 is the mold section 40 whichhas partly embedded therein or at least supported thereby the waxpattern or model 4| from which projects oneor more sprue formers 42which like the pattern 4| are formed of wax. 'The mold portion '48,which is made of cementitious material, is secured to the surface lii'bypieces of So called sticky wax 43. It will be understood that the mold40 and parts associated therewith are positioned on the base l5.at itsmore advantageous position.v After this has been done the walls of theboxing are arranged in position.

The curtain l8'is now wound around the base l5 with its lower edge onthe shoulder or ledge 18 until its free edge '39 substantially 'meetsthe fixed edge 37 whereuponiitis arranged outwardly as shown clearly inFig. 3. The key'28 is 'then inserted through the aperture '24 in car '22,in such a way as to have the projecting portion of the curtain 38within its slot 38 and embraced. by the key arms 3i and'32. The operatorpushes'the key downwardly until the lower end thereof is within theaperture 24 in ear23 and the collar shoulder .34 resting on the uppersurface 'dffthe ear '22 whereupon the key is turned in a clockwisedirection as seen in Figs. 2 and 3 for drawing the curtain tightlyaround the base IS. The key is then looked in its tightened position bythe thumb screw 2E.

The assembly is now placed on a mechanical vibrator and the investmentor cementitious material while in its fluid stage poured into the boxingto form the upper half or upper portion 44 of the mold. In other wordsthe cementitious material forming the mold portion 44 is poured into thebox to enclose the portion of the patterns 4i projecting from the moldportion 40 and to enclose the sprue formers 42. A hollow cup likedepression 45 is now formed in the top surface of the mold portion 44around the sprue formers and acts as the crucible in which the metal issubsequently reduced to a fluid state.

The entire mechanism is now set aside to allow the cementitious mold toset or harden as is the usual practice. It should be noted that sincethe curtain 38 is formed of transparent material the operator wasobserving the filling in of the plasti which formed the mold portion 44and could readily control the flow of this material to be sure allcrevices and undercuts were properly encased.

After the mold has set or hardened the thumb screw 26 is loosened topermit the renewal of the key 28 and thereby releases the free end ofthe curtain 39 whereupon said curtain is pulled from around the mold andthe completed mold removed for operation thereon as is the usualpractice.

In the modified mechanism disclosed in Figs. 6 to 10 inclusive asubstantially identical base member I5 is employed and is securedthereto an upstanding post 45 which is shorter than the post l5 aboveand devoid of ears 22 and 23. The post 46 has projecting outwardlytherefor substantially midway of its height a screw 41. Cooperating withthe post 46 is a second post 48 of a length substantially equal to thatof post 46 and having an aperture '49 through which projects the screw41. Projecting from the upper end of the post 48, from each sidethereof, is respectively an arm 50 and 5| arcuate shaped substantiallyto the diameter of the interior of the mold wall or curtain.

In this form of the invention the curtain 38 has both ends free of thepost'4l'i'and respectively provided with a notch 52 and 53 which whenthe curtain is in position receive the screw 41.

In the operation of this modified boxing construction the post 48 andthe curtain 38' are removed entirely from the base l5 while the moldportion 48 and part carried thereby are being mounted and secured tosaid base. After this the curtain is arranged around the base I5 againwith its lower edge on the shoulder l8 and with the notches 52 and 53receiving the screw 41. The post 48 is then placed against theoverlapped ends of the curtain 38 with the screw 41 projecting throughthe aperture 49 and the arms 50 and El encircling the upper end of theboxing sides. The thumb screw 54 is now screwed on to the screw 47 forclamping the posts 48 and 46 to one another with the curtain endstherebetween.

The further operation or filling of this box is identical with thatabove. The modified boxing mechanism through its arms 56 and 5| has theadvantage of supporting the upper end of the boxing wall against outwardsagging due to the weight of the cementitious material therein.

In order to insure a tight fit of the lower 'end of the curtain 38against the base 15 use may be made of an elastic band 55 placed aroundsaid lower end of the boxing wall and shown in phantom lines in Fig. 6and solid lines in Fig. 9. This tight fit of the housing wall in thestructure illustrated in Figs. 1 to 5 inclusive is, of course, obtainedby a further tightening of the key 38.

What is claimed is:

1. In a mechanism of the class described the combination of a basemember, a flexible transparent curtain having its lower edge encirclingand tightly engaging the base member and upstanding therefrom to form awall therearound, and means for securing the curtain in its encircledwall forming position.

2. In a mechanism of the class described the combination of a basemember, a flexible transparent curtain having its lower edge encirclingand tightly engaging the base member and upstanding therefrom to form awall therearound, means for securing the curtain in its encircled wallforming position, and means upstanding from said base for ridgedlysupporting a portion of the curtain in its upright position andconstituting part of the curtain securing means.

3. In a mechanism of the class described the combination of a basemember, a post upstanding from the base member at one point on itsperimeter, a curtain removably having its lower edge encircling andtightly engaging the base member and upstanding to form walls around theperimeter of the base member, and means cooperating with said post forsecuring the curtain in it encircling position relative to the basemember.

4. In a mechanism of the class described the combination of a basemember, said base member having a radial shoulder projecting therefromabove the bottom of the base member, a post upstanding from said basemember at one point on its perimeter, a transparent curtain having itslower edge resting on the shoulder and having its lower end encirclingand tightly engaging the base member above the shoulder, and the curtainupstanding relative the base member to form walls thereabove with thecurtain ends adjacent one another along the rear face of the post, andmeans cooperating with said post for securing the ends in adjacentposition and relative to the base.

5. In a mechanism of the class described the combination of a basemember, said base member having a radial shoulder projecting therefromabove the bottom of the base member, a post upstanding from said basemember at one point on its perimeter, a transparent curtain having itslower edge resting on the shoulder and having its lower end encirclingand tightly engaging the base member above the shoulder, and the curtainupstanding relative the base member to form walls thereabove with thecurtain ends adjacent one another along the rear face of the post, meanscooperating with said post for securing the ends in adjacent positionand relative to the base, including a key rotatably supported by thepost for drawing the ends of the curtain toward one another and securingthem in this position.

6. In a mechanism of the class described the combination of a basemember, said base member having a radial shoulder projecting therefromabove the bottom of the base member, a post up standing from said basemember at one point on its perimeter, a transparent curtain having itslower edge resting on the shoulder and having its lower end encirclingand tightly engaging the base member above the shoulder, and the curtainupstanding relative the base member to form walls thereabove with thecurtain ends adjacent one another along the rear face of the post, andmeans cooperating with said post for securing the ends in adjacentposition and relative to the base, including a second post adapted tooverlap the first post with the ends of the curtain between them andsecured in this position.

'7. In a mechanism of the class described the combination of a basemember, said base member having a radial shoulder projecting therefromabove the bottom of the base member, a post upstanding from said basemember at one point on its perimeter, a transparent curtain having itslower edge resting on the shoulder and having its lower end encirclingand tightly engaging the base member above the shoulder, and the curtainupstanding relative the base member to form walls thereabove with thecurtain ends adjacent one another along the rear face of the post, meanscooperating with said post for securing the ends in adjacent positionand relative to the base, including a second post adapted to overlap thefirst post with the ends of the curtain between them and secured in thisposition, and arms extending from the second post substantiallyencircling the upper end of the curtain walls.

8. A boxing for cementitious molds comprising a base member havingupstanding from one point on its periphery a post, said base having ashoulder projecting from its periphery above the bottom thereof, acurtain having one end secured to the post and encircling the base withits lower edge on the base shoulder and its free end adjacent its fixedend, arms projecting from the upper and lower ends of the post, a keyjournaled in said arms and having the body portion split to receive thefree end of the curtain whereby rotation of the key tightens the curtainagainst the periphery of the base, and means for locking the key in itscurtain tightening position.

9. A boxing for cementitious molds comprising a base member havingupstanding from one point of its periphery a post, said base memberhaving projecting from its periphery a shoulder, a curtain enclirclingthe base member with its lower edge on the shoulder and its endsoverlapped and against the back surface of the post, a screw proj ectingfrom the rear surface of the post through the overlapped ends of thecurtain, a second post co-extensive in area with the first post andoverlapping same with the overlapped ends of the curtain therebetweenand a thumb nut on said screw for clamping the posts against one anotherand securing the ends of the curtain therebetween.

10. A boxing for cementitious molds comprising a base member havingupstanding from one point of its periphery a post, said base memberhaving projecting from its periphery a shoulder, a curtain encirclingthe base member with its lower edge on the shoulder and its endsoverlapped and against the back surface of the post, a screw projectingfrom the rear surface of the post through the overlapped ends of thecurtain, a second post co-extensive in area with the first post andoverlapping same with the overlapped ends of the curtain therebetween, athumb nut on said screw for clamping the posts against one another andsecuring the ends of the curtain therebetween, and arms projecting fromthe upper end of said second post for encircling the upper end of thecurtain when in encircling position. on the base.

HAROLD L. FOWLER. AUGUST L. WEYHING.

